correct usage of "As of"

I found the undermentioned sentence a few months ago:

“As of 5 January 2010, we no longer offer our own services”

I know exactly what it means, it must mean “since” but it has to be used without present perfect. To tell you the truth I’ve never heard it using in spoken english yet. My question is, in what cases can I use “as of” and may I use it in spoken english, without so much as People stare at me weirdly.

Thanks

Good question TIE! People might consider you a little prim and proper if you used it in spoken English in an informal setting. It tends to be reserved for writing, usually formally and often relates to business and industry.

You might hear it in a business meeting or trade union meeting.

Then, according to it, do you suggest me ignoring it in spoken English? The problem is, I’m likely to word too complicated even in my first language - just simply I’d like to widen my knowledge and vocabulary.

I’ve just had a listening lesson separated from VOA Special English Report and as far as I could remember, it’s about an education program called three year graduation. There was also an ‘as of’. My teacher explained that it meant From. After some time I thought it was all right. What do you think?